This invention relates to purified non-specific suppression factor and to a process for isolating the same.
A degree of immunosuppression commonly accompanies a variety of virus-induced tumors, chemically induced tumors, experimental amyloidosis, liver cirrhosis, infection and pregnancy. The precise mechanism is not known, but numerous reports indicate that non-cytotoxic immunosuppressive humoral factors in normal or malignant serum may play a role. Unlike the serum-blocking factors that contain specific antibodies to tumor associated antigens, the non-specific suppressive factors inhibit responses to a spectrum of unrelated antigens. The cellular origin of these factors is not known. It has been shown that malignant ascites fluids are abundant sources of these factors and that tumor extracts also contain non-specific suppressive factors. It also has been shown that the suppressive factors in malignant human ascites fluids (three ovarian and two colonic cancer ascites fluids) exist as macromolecular complexes and that the active component can be extracted and purified as a smaller M.W. (50,000), potent immunosuppressive moiety (Oh et al, Fed. Proc. 39:1614). This was shown to suppress T-dependent antibody responses in vivo and T-dependent mitogen responses in vitro at microgram concentrations per ml. This suppressive factor could not be identified with any of the plasma proteins.
It would be desirable to provide purified non-specific suppressive factor in order to provide a satisfactory antigenic for producing antibody to the non-specific suppressive factor by conventional animal immunization techniques or by the hybridoma techniques of Kohler and Milstein. Such antibodies can be tagged with radioactive labels, such as iodine, technetium-99m or the like or fluorescent markers of other conventional tags to provide an assay means for measuring the level of non-specific suppressive factor in a patient's blood serum. Furthermore, such antibodies would be useful for treating the patient's plasma to provide contact between the antigen and antibody thereby to effect antigen removal from the plasma by antigen-antibody interaction. In addition, the purified non-specific suppressive factor is useful in treating patients afflicted with a disease associated with an overactive immunosuppressive condition such as rheumatoid arthritis, multiple sclerosis, severe allergy or lupus.